foo.c: In function 'main':
foo.c:18:1: warning: 'gets' is deprecated [-Wdeprecated-declarations]
   18 | { char s1[9999]; gets(s1);
      | ^
In file included from /usr/include/stdio.h:867,
                 from foo.c:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:235:1: note: declared here
  235 | gets (char *__str)
      | ^~~~
foo.c:19:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
   19 |  char s2[9999];  gets(s2);
      |  ^~~~
In file included from /usr/include/stdio.h:867,
                 from foo.c:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:235:1: note: declared here
  235 | gets (char *__str)
      | ^~~~
foo.c:18:18: warning: ignoring return value of 'gets', declared with attribute warn_unused_result [-Wunused-result]
   18 | { char s1[9999]; gets(s1);
      |                  ^~~~~~~~
foo.c:19:18: warning: ignoring return value of 'gets', declared with attribute warn_unused_result [-Wunused-result]
   19 |  char s2[9999];  gets(s2);
      |                  ^~~~~~~~
foo.c: In function 'Concat1':
foo.c:8:7: warning: 'i' is used uninitialized in this function [-Wuninitialized]
    8 |  s1[n1+i]=0;
      |     ~~^~
foo.c: In function 'Concat':
foo.c:15:7: warning: 'i' is used uninitialized in this function [-Wuninitialized]
   15 |  s1[n1+i-2]=0;
      |     ~~^~
/usr/bin/ld: /tmp/ccgg9MHV.o: in function `main':
foo.c:(.text.startup+0x4e): warning: the `gets' function is dangerous and should not be used.

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